The present invention relates generally to surgical tourniquets. More particularly, the present invention relates to various aspects of a system and method for controlling pressure in a surgical tourniquet.
Surgical tourniquets are widely used during surgical procedures to occlude the flow of blood in a portion of a limb during the procedure, particularly in connection with arthroscopic procedures relating to the hand, wrist, elbow, foot, and knee, in which the existence of a bloodless field in the appropriate portion of a patient""s limb may be required. Surgical tourniquets are similarly useful in other procedures in which the creation of a bloodless field is desirable, including nerve grafting and harvesting. It is particularly important in certain procedures that a surgeon be able to shut off the flow of blood extremely quickly during the procedure. Yet prior art surgical tourniquets typically require seven seconds or more for inflation before blood flow may be occluded. It is equally important that pressure be evenly maintained by a surgical tourniquet despite the manipulation by a surgeon of the limb in which blood flow is being occluded by the tourniquet, which manipulation tends to affect the pressure within the tourniquet. It is also important that the surgical tourniquet be easy to use and physically stable so that the surgeon may focus his attention on other aspects of the surgery.
It is therefore an object of the present invention to provide a dual reservoir equilibrium surgical tourniquet allowing swift inflation and deflation.
It is a further object of the present invention to provide a surgical tourniquet that can be inflated in less than five seconds.
It is a still further object of the present invention to provide a method for detecting air leaks in a surgical tourniquet.
It is a still further object of the present invention to provide a surgical tourniquet that from an inflated state may be deflated, reset to default values, adjusted to new values, or turned off.
It is a still further object of the present invention to provide a surgical tourniquet with a housing fitting around a pole and with a center of gravity within the pole.
It is a still further object of the present invention to provide a surgical tourniquet with an easy to use graphical user interface.
It is a still further object of the present invention to provide a method for detecting stuck valves in a surgical tourniquet.
The present invention is directed to a system and method of controlling the pressure within a surgical tourniquet so as selectively to occlude blood flow within a portion of a limb of a patient. The pressure within an inflatable cuff surrounding a portion of a limb of a patient is decreased by automatically opening a first valve connected to a controller and located within a first conduit between an inflatable bladder and the inflatable cuff, when the pressure in the inflatable cuff is greater than that in the inflatable bladder. The pressure within an inflatable cuff surrounding a portion of a limb of a patient is increased by automatically opening a first valve connected to a controller and located within a first conduit between an inflatable bladder and the inflatable cuff, when the pressure in the inflatable cuff is less than that in the inflatable bladder.
In another aspect, the present invention is directed to a system and method of controlling the pressure within a surgical tourniquet so as selectively to occlude blood flow within a portion of a limb of a patient, wherein the pressure within an inflatable cuff surrounding a portion of a limb of a patient is automatically altered by opening a first valve connected to a controller and located within a first conduit between an inflatable bladder and the inflatable cuff, and wherein the pressure within the inflatable cuff may be increased by a pump from a pressure equal to that of the surrounding atmosphere to a pressure sufficient to occlude the flow of blood in a portion of the patient""s limb within five seconds.
In another aspect, the present invention is directed to a system and method of detecting a leak in a surgical tourniquet, including an inflatable cuff, wherein the pressure of gas within the inflatable cuff is increased until a target pressure is reached. The pressure of gas contained within the inflatable cuff is then repeatedly measured with a pressure sensor coupled to the inflatable cuff and connected to a controller. Data relating to each extraneous change in pressure are stored in a memory. All extraneous changes in pressure are then compared using predetermined criteria to determine if a leak has occurred.
In another aspect, the present invention is directed to a surgical tourniquet, including an inflatable cuff, containing a quantity of gas, and a controller, wherein from an inflated state the surgical tourniquet may enter a deflated state, a set state, a default display state, or an off state.
In another aspect, the present invention is directed to a surgical tourniquet, including an inflatable cuff, a controller connected to the inflatable cuff, and an electronic display connected to the controller and mounted in a housing selectively closed around a pole, wherein the center of gravity of the housing is located within the pole.
In another aspect the present invention is directed to a surgical tourniquet, including an inflatable cuff, a controller connected to the inflatable cuff, and a display connected to the controller, wherein a user controls the surgical tourniquet by means of a graphical user interface displayed on said display.
In another aspect, the present invention is directed to a method of detecting a stuck solenoid valve in a surgical tourniquet, wherein the current, if any, flowing through the solenoid valve is sensed. It is determined whether the solenoid valve is open based on the amount of current flowing through the solenoid valve. Whether the solenoid valve should be open is determined based on the current state of the surgical tourniquet. Whether the solenoid valve is stuck is then determined based on a comparison of whether the solenoid valve is open and whether it should be open, and, if the solenoid valve is stuck, any short circuited output is turned off.
In accordance with a further aspect, the present invention is directed to a method for controlling the operation of a surgical tourniquet. An input setting is received from a user through a graphical user-interface, wherein the input setting corresponds to a user-selected target pressure to be maintained in the surgical tourniquet during a medical procedure. The user-selected target pressure is compared, with a controller coupled to the user-interface, to a range of acceptable target pressures. If the user-selected target pressure is outside of the range of acceptable target pressures, the user-selected target pressure is rejected by the system. Alternatively, if the user-selected target pressure is within the range of acceptable target pressures, the surgical tourniquet is pressurized in accordance with the user-selected target pressure.
In accordance with a still further aspect, the present invention is directed to a further method for controlling the operation of a surgical tourniquet. In this further method, an input setting is received from a user through a graphical user-interface, wherein the input setting corresponds to a user-selected time period during which a target pressure is to be maintained in the surgical tourniquet during a medical procedure. The user-selected time period is compared, with a controller coupled to the user-interface, to a range of acceptable time periods. If the user-selected time period is outside of the range of acceptable time periods, the user-selected time period is rejected by the system. Alternatively, if the user-selected time period is within the range of acceptable time periods, a timer is set in the surgical tourniquet in accordance with the user-selected time period. An audible alarm is then sounded upon expiration of the user-selected time period. In a particularly preferred embodiment, a user can optionally delay deflation of the surgical tourniquet for successive predetermined periods of time following expiration of the user-selected period of time by entering delay commands through the graphical-user interface. Entry of each delay command serves to silence an alarm resulting from expiration of a previous time period and also serves to reset the timer for a further predetermined time period, after which the alarm sounds again. After a predetermined number of iterations of this process, the system does not accept further delay commands and the alarm remains in a continuous on state.
In accordance with yet a further aspect, the present invention is directed to a still further method for controlling the operation of a surgical tourniquet. An input command is received from a user through a graphical user-interface, wherein the input command corresponds to an instruction to deflate the surgical tourniquet. Shortly thereafter, the pressure in the surgical tourniquet is sensed and the sensed pressure is compared with a pressure corresponding to the surgical tourniquet in its deflated state. If the sensed pressure exceeds the pressure corresponding to the surgical tourniquet in its deflated state by more than a predetermined amount, then an alarm is sounded.